Carbohydrates and dental caries

Carbohydrates and dental caries

The resident bacteria in the mouth ferment carbohydrates to yield acidic end-products (mainly lactic acid but also some formic, acetic, and propionic acids), which result in a drop in dental plaque pH. When the pH falls below 5.5, the dental enamel dissolves in the plaque fluid and repeated exposure to periods of very low pH can lead to caries. Not all carbohydrates are equally cariogenic. The sugars found commonly in human foods, e.g., sucrose, fructose, glucose, and maltose, are all readily fermented by bacteria in the mouth. Lactose, galactose, and starches are less cario-genic, while sugar alcohols such as xylitol (used as a sweetener in some confectionery and chewing gums) are noncariogenic. Eating sugars with meals reduces the risk of caries, as does the consumption of cheese, which provides phosphates to prevent demineraliza-tion and to encourage demineralization of the enamel.

Fluoride ingestion in foods and drinking water or topical application via toothpastes and mouth rinses prevents dental caries. Too much fluoride in drinking water can cause fluorosis, which damages the skeleton and teeth. The optimum concentration of fluoride in temperate areas of the world is 1 mg/l, falling to 0.6 mg/l in tropical climates where fluid intake is likely to be greater.